the migrtaion or people from rural area communities to large developed cities is increasing in many developing countries .Why do you think this happens and what problem can this cause

Nowadays, people from rural areas moved toward cities ,because of which cities population is increasing day by day .the main cause of this is that there is less facilities in rural area .and mostly rural even have no basic facilitiess such as hospital, school etc .so there moving toward cities .it will cause over population city and it will become more problems in cities